Chromatography is a technique used to separate components of a mixture based on differences in their physical or chemical properties. There are several types, categorized mainly by the phase that moves (mobile phase) and the phase that stays fixed (stationary phase). Here’s an overview:
1. Column Chromatography
- Principle: Separation based on adsorption or partitioning between stationary and mobile phases.
- Stationary phase: Solid (like silica gel or alumina) packed in a column.
- Mobile phase: Liquid that flows through the column.
- Uses: Purifying organic compounds.
2. Paper Chromatography
- Principle: Separation based on solubility and adsorption.
- Stationary phase: Special chromatography paper.
- Mobile phase: Solvent that moves via capillary action.
- Uses: Separating small molecules like amino acids, sugars, or plant pigments.
3. Thin Layer Chromatography (TLC)
- Principle: Similar to paper chromatography but faster and more sensitive.
- Stationary phase: Thin layer of silica gel or alumina on a glass or plastic plate.
- Mobile phase: Solvent that travels up the plate.
- Uses: Checking purity of compounds, monitoring reactions.
4. Gas Chromatography (GC)
- Principle: Separation based on volatility and interaction with stationary phase.
- Stationary phase: Liquid or polymer coated on a column inside a gas chromatograph.
- Mobile phase: Inert gas (like helium).
- Uses: Analyzing volatile compounds like gases, essential oils, and pollutants.
5. High-Performance Liquid Chromatography (HPLC)
- Principle: High-pressure liquid moves through a column packed with fine particles.
- Stationary phase: Silica or polymer-based material.
- Mobile phase: Liquid solvent pumped under high pressure.
- Uses: Pharmaceuticals, biomolecules, food analysis.
6. Ion-Exchange Chromatography
- Principle: Separation based on charge differences.
- Stationary phase: Resin with positive or negative charges.
- Mobile phase: A buffer solution.
- Uses: Purifying proteins, amino acids, nucleotides.
7. Affinity Chromatography
- Principle: Separation based on specific biological interactions.
- Stationary phase: Matrix with ligands that bind specific molecules.
- Mobile phase: Buffer solution.
- Uses: Purifying enzymes, antibodies, or other biomolecules.